Issue Archive

An assembly of devices provides for both humidification of the reactant gas streams of a fuel cell and removal of the product water (the water generated by operation of the fuel cell). The assembly includes externally-sensing forward-pressure regulators that supply reactant gases (fuel and oxygen) at variable pressures to ejector reactant pumps. The ejector supply pressures depend on the consumption flows. The ejectors develop differential pressures approximately proportional to the consumption flow rates at constant system pressure and with constant flow restriction between the mixer-outlet and suction ports of the ejectors. For removal of product water from the circulating oxygen stream, the assembly includes a water/gas separator that contains hydrophobic and hydrophilic membranes. The water separator imposes an approximately constant flow restriction, regardless of the quality of the two phase flow that enters it from the fuel cell. The gas leaving the water separator is nearly 100 percent humid. This gas is returned to the inlet of the fuel cell along with a quantity of dry incoming oxygen, via the oxygen ejector, thereby providing some humidification.

This robot could move along a ferromagnetic structure in any orientation. A versatile mobile telerobot, denoted the magnetically attached multifunction maintenance rover (MAGMER), has been proposed for use in the inspection and maintenance of the surfaces of ships, tanks containing petrochemicals, and other large ferromagnetic structures. As its name suggests, this robot would utilize magnetic attraction to adhere to a structure. As it moved along the surface of the structure, the MAGMER would perform tasks that could include close-up visual inspection by use of video cameras, various sensors, and/or removal of paint by water-jet blasting, laser heating, or induction heating.

The proportionality between penetration force and penetration depth is exploited.
Feedback control of the penetration force applied to a pin tool in friction stir welding has been found to be a robust and reliable means for controlling the depth of penetration of the tool. This discovery has made it possible to simplify depth control and to weld with greater repeatability, even on workpieces with long weld joints.

Medical oxygen liquefiers could operate more efficiently. Two improvements in heat-transfer design have been investigated with a view toward increasing the efficiency of refrigerators used to liquefy gases. The improvements could contribute to the development of relatively inexpensive, portable oxygen liquefiers for medical use.

The goal is to increase production yields. A micromachining process for the fabrication of vibratory microgyroscopes from silicon wafers, and aspects of the microgyroscope design that are inextricably linked with the fabrication process, have been modified in an effort to increase production yields from perspectives of both quantity and quality. Prior to the modifications, the effective production yield of working microgyroscopes was limited to one or less per wafer. The modifications are part of a continuing effort to improve the design and increase production yields to more than 30 working microgyroscopes per wafer.

Anchor Industries supplies tents and fabric products to the outdoor amusement and entertainment industries, and municipalities. With their experience in producing portable structures, Anchor re-entered the military market of vehicle maintenance shelters (VMS). The first Anchor VMS, designed several years ago to compete with another company’s lightweight maintenance enclosure (LME), was overpriced compared to similar products in the U.S. and Europe, so the company sought to create a more competitive and efficient shelter.

Selected heat treatments are performed between and after fabrication steps.Five metallurgical treatments have been tested as means of stabilizing mirrors that are made of aluminum alloy 6061 and are intended for use in cryogenic applications. Aluminum alloy 6061 is favored as a mirror material by many scientists and engineers. Like other alloys, it shrinks upon cool-down from room temperature to cryogenic temperature. This shrinkage degrades the optical quality of the mirror surfaces. Hence, the metallurgical treatments were tested to determine which one could be most effective in minimizing the adverse optical effects of cooldown to cryogenic temperatures. Each of the five metallurgical treatments comprises a multistep process, the steps of which are interspersed with the steps of the mirror- fabrication process. The five metallurgical- treatment/fabrication–process combinations were compared with each other and with a benchmark fabrication process, in which a mirror is made from an alloy blank by (1) symmetrical rough machining, (2) finish machining to within 0.006 in. (˜ 0.15 mm) of final dimensions, and finally (3) diamond turning to a mirror finish. Two specimens ? a flat mirror and a spherical mirror ? were fabricated in each case. The blanks for all the specimens were cut from the same plate of aluminum alloy 6061-T651. (The suffix “T651” denotes a stress-relieving treatment that involves reducing residual stresses by mechanical stretching of the previously untreated alloy.) Of the five metallurgical-treatment/fabricationprocess combinations tested, the one found to exert the greatest stabilizing effect comprises the following ten steps:

Question of the Week

This week's Question: Last week, Elon Musk, chief executive of Tesla, said that the electric car maker would introduce autonomous technology, an autopilot mode, by this summer; the technology will allow drivers to have their vehicles take control...